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The Impact of Tropical Cyclones on Upper-Atmospheric Chemistry Using a High-Resolution Chemical Transport Model and Aircraft Observations

This research focuses on the transport of chemical species to the upper troposphere/lower stratosphere (UTLS) by tropical cyclones (TCs). Species such as carbon monoxide, nitrogen oxide, ozone, etc. have been found to exert a greater influence on climate change at these high altitudes than if remaining near the surface. Typhoon Mireille (1991) is examined in the western North Pacific (WNP) Ocean basin using in situ aircraft-derived chemical data from NASA's Pacific Exploratory Mission-West A field project. I also use the Weather Research and Forecasting (WRF) model with chemistry (WRF-Chem) at an innermost grid spacing of 3 km to explicitly resolve the convection being studied. Results show that pollution from distant sources are ingested by Mireille and subsequently lofted by eyewall convection to the UTLS, enhancing concentrations in this region. Flux calculations suggest that a strong TC, such as Mireille, can impact UTLS chemistry as much as a continental middle latitude cyclone. Improved understanding of atmospheric chemistry in the WNP basin is important, especially in the context of increasing Asian emissions and a changing climate. Furthermore, since it has been hypothesized that global warming will lead to more intense storms, it is important to understand TCs’ role in chemical transport.